Using an imx6ull SOM with an IRIS carrier board and want to redefine the SODIMM_45 to be used as a "gpio-poweroff" 3v3 signal on "Shutdown -h now"

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To achieve your goal of redefining SODIMM_45 (gpio_129) as a GPIO power-off signal on shutdown for the iMX6ULL on the Iris Carrier Board, you will need to modify the device tree. Here are the steps to do so:

  1. Remove SODIMM_45 (gpio_129) as a ‘wakeup’ signal:

    You need to locate the device tree node that configures SODIMM_45 as a wakeup signal and remove or disable it. This is typically found in the iomuxc node or a similar node in the device tree.

  2. Redefine SODIMM_45 (gpio_129) as a GPIO power-off signal:

    You will need to add a new node to configure SODIMM_45 as a GPIO power-off signal. This involves setting the pinmux and configuring the GPIO power-off driver.

Here is an example of how you can modify the device tree:

&iomuxc {
    pinctrl-names = "default";
    pinctrl-0 = <&pinctrl_hog>;

    pinctrl_hog: hoggrp {
        fsl,pins = <
            MX6UL_PAD_SNVS_TAMPER1__GPIO5_IO01 0x1b0b0
        >;
    };
};

&gpio5 {
    gpio-poweroff {
        compatible = "gpio-poweroff";
        gpios = <&gpio5 1 GPIO_ACTIVE_HIGH>;
        status = "okay";
    };
};

In this example:

  • MX6UL_PAD_SNVS_TAMPER1__GPIO5_IO01 corresponds to SODIMM_45 (gpio_129).
  • The gpio-poweroff node is added under the gpio5 node, specifying the GPIO pin and its active state.

Steps to Apply the Changes:

  1. Edit the Device Tree Source (DTS) File:

    • Locate the device tree source file for your board, typically found in the arch/arm/boot/dts/ directory of the Linux kernel source.
    • Apply the changes as shown in the example above.

  2. Recompile the Device Tree Blob (DTB):

    • Recompile the device tree source file to generate the updated DTB file.
    make ARCH=arm dtbs

  3. Deploy the Updated DTB File:

    • Copy the updated DTB file to the boot partition of your device, replacing the existing DTB file.

  4. Reboot the Device:

    • Reboot your device to apply the changes.

Additional Notes:

  • Ensure that the GPIO pin is not being used by any other function in the device tree.
  • Verify the pinmux settings to ensure that the pin is correctly configured as a GPIO.

By following these steps, you should be able to redefine SODIMM_45 (gpio_129) as a GPIO power-off signal on shutdown for your iMX6ULL on the Iris Carrier Board.

Please, also check if these links can help you solve your problem:

Device Tree Customization/ Device Tree Overlays to Enable/multiplex GPIO.